1. Field of the Invention
The present invention concerns a method of identifying foreign bodies in packaged beverages, where the package and the beverage are translucent, and the foreign bodies have a density greater than that of the beverage. The invention moreover concerns devices for performing the method and uses of said devices.
2. Description of the Related Art
Methods of this type are known. In the performance of these known methods, the foreign bodies are identified manually in that an operator manually turns the package, while observing whether foreign bodies move in the beverage. These known methods are not useful for identification of small foreign bodies, such as glass splinters, since they are frequently very difficult to observe. Further, it is not possible to identify foreign bodies with certainty in dark beverages owing to poor translucency. Finally, it has been found in practice that a large batch of beverages has to be rejected each time foreign bodies are observed in these. The reason is that the manual identification is performed only once an hour, and that it is desired not to place doubtful beverages with impurities on the market. Thus, the method is very expensive in the event that foreign bodies are observed in the beverages.
FR 2 607 589 discloses a method and a system for automatic identification of foreign bodies in glass bottles, in particular champagne bottles. The foreign bodies are detected using a spot scanner, while the bottle is turned about a vertical and a horizontal axis. However, this method does not enable the foreign bodies to be distinguished from carbonic acid and air bubbles, for which reason the method has been found to be unuseful in practice. Furthermore, the method cannot be applied to dark liquids at all.
Further, U.S. Pat. No. 5,072,108 discloses a method wherein the bottle to be inspected is rotated rapidly and is photographed durig the rotation. Scratches in the surface of the bottle will hereby be imaged as horizontal lines, while the foreign bodies in the non-rotating liquid can easily be identified. However, this method cannot be used for dark liquids either. It may likewise be a problem to detect foreign bodies at the domed bottom of the bottle.